Wheelchair, wheel for wheelchair, and method of producing wheel for wheelchair

ABSTRACT

A wheel for a wheelchair according to the present invention includes: an outer wheel or ring mounted on the inner periphery of a tire; an inner ring connected with a wheelchair frame (concentric with the outer ring and positioned inside the outer ring); a plurality of rolling elements interposed between the outer ring and the inner ring, arranged with an interval between each other in a circumferential direction; and a plurality of spacers (retainers or interval-holding members) for holding intervals between the rolling elements. Each spacer is in a shape extending along a circumferential direction of the outer ring and the inner ring, and is provided between the rolling elements respectively. The wheel does not have a hub and spokes, and the inner peripheral side does not rotate, and further the wheel weight is light. The wheelchair of the present invention includes the wheel for a wheelchair.

TECHNICAL FIELD

The present invention relates to wheelchairs, wheels for a wheelchair,and a method of manufacturing wheels for a wheelchair.

BACKGROUND ART

FIG. 11 is a perspective view showing a conventional self-travelingmanual wheelchair 50. The wheelchair 50 has such a configuration thatwheels are mounted to a chair unit 60. The wheels include large drivewheels 51 mounted on the transverse sides of the chair unit 60, andsmall casters 52 mounted on both front corners. The drive wheel 51 hassuch a configuration that a tire 53 is fixed to a hub 55 with spokes 54,and that a hand rim 56 for transmitting a driving force by a hand of auser is mounted to the drive wheel 51. The chair unit 60 consists of aseat surface 61, a back rest 62, arm rests 63, leg supports 64, and aframe 65 for connecting them so as to form the chair unit. Further, onthe rear side top parts of the frame 65, grips 65 a used when a carrierpushes the wheelchair are mounted.

The drive wheel 51 is connected of the chair unit 60 by mounting a hubmounting part 57 fixed to the frame 65 to the hub 55. Further, thecasters 52 are connected in such a manner that holding members 59 b aremounted to axes 59 a provided at the center of the casters 52, and theholding members 59 b are fixed to the frame 65.

Although the configuration of the drive wheel 51 of a typically usedwheelchair is that the tire 53 is fixed to the hub 55 with the spokes54, as shown in FIG. 11 (conventional example 1), a drive wheel withouta hub and spoken as recently been proposed. Specifically, as shown inFIG. 12 [A is a side view showing a wheelchair of a conventional example2, B and C are perspective views thereof], a drive wheel 71 includes thetire 53, a rail part 72 mounted on the inner periphery thereof, andthree pulleys 73 which are connected with the frame 65 of the wheelchairrespectively. When the tire 53 rotates, the pulleys 73 travel on therail part 72 in a state that the positions thereof are fixed withrespect to the frame 65 (conventional example 2). (For example, seeJapanese Patent Application Laid-Open Publication No. 2000-342632 (FIG.1, FIG. 2, FIG. 5, and FIG. 6), Japanese Utility-Model ApplicationLaid-Open Publication No. 62-66629, and Japanese Patent ApplicationLaid-Open Publication No. 47-32550).

Further, metallic rings which are doubled inside and outside like arolling bearing mounted via rollers are proposed as another example of adrive wheel without a hub and spokes (conventional example 3). Forexample, as shown in FIG. 13 [A shows a wheelchair of the conventionalexample 3, which is a partially broken perspective view of a drive wheel81 thereof, and B is a sectional view taken along the line B-B shown inA.], a roller chain 75 compose a plurality of rollers 79 and links 76 toconnect the rollers 79, and the roller chain 75 is provided between, andis so configured that an outer ring 78 mounted on the inner periphery ofa tire 53 and an inner ring 77 mounted inside thereof and mounted to theframe 65 (see Japanese Patent Publication No. 2960161 (p. 4, FIG. 1 toFIG. 3) and U.S. Pat. No. 4,593,929 (FIG. 65, FIG. 66)).

In these conventional examples 2 and 3, there is no spoke 54, differentfrom the conventional example 1. Therefore, when a baggage basket 70 isprovided right under the seat surface 61 of a wheelchair, this providesan advantage that a baggage can be put into or taken out of the baggagebasket 70 easily (see FIG. 12).

DISCLOSURE OF THE INVENTION

The drive wheel of the conventional example 3 has an advantage thatclothes are not rubbed and damaged even if the clothes contact the drivewheel since the inner peripheral side does not rotate. However, sincethe metallic wheels are doubled and a plurality of rollers are provided,the weight is heavy. In particular, a large force is required as a forceto push the hand rims 56 when starting the wheelchair. Further, if thewheelchair itself is heavy, a large burden is placed on a carer, whenthe carer holds up the user on the wheel chair together with thewheelchair to walk up and down stairs or the like. In addition, the costof a drive wheel of the conventional example 3 is high.

In view of the above, an object of the present invention is to provide awheel for a wheelchair, a wheelchair itself, and a method ofmanufacturing a wheel for a wheelchair, in which the weight of the wheelis not heavy and the inner peripheral side of the wheel does not rotate.

A wheel for a wheelchair according to the present invention achievingthis object comprises: an outer ring mounted on the inner periphery of atire; an inner ring which is positioned concentrically inside the outerring and fitted on a wheelchair frame; a plurality of rolling elementsinterposed between the outer ring and the inner ring, each rollingelement being spaced out at intervals in a circumferential direction;and a plurality of spacers for maintaining said intervals between therolling elements. Each spacer is in an elongated shape extending along acircumferential direction of the outer ring and the inner ring, and isprovided between the rolling elements, respectively.

The rolling element is a part receiving the weight applied from theinner wheel to the outer ring (or from the outer ring to the innerring), which is required to have a sufficient intensity, therefore it isdifficult to make the rolling element itself lighter. However, thespacer for the interval between the rolling elements is only required toserve to prevent a contact between the rolling elements, therefor such ahigh intensity is not required, whereby it can be made lighter. Bymaking the spacer have a shape extending along a peripheral direction,that is, a relatively long shape as described above, it is possible toreduce the number of rolling elements by increasing the arrangementratio of the spacers, which can be made lighter, in a peripheraldirection between the outer wheel and the inner ring, thereby, theweight of the wheel can be reduced as a whole. In addition, theconfiguration is simplified by reducing the number of rolling elements,therefore reducing the manufacturing cost.

In a case of a typical rolling bearing, a large number of rollingelements are disposed by making the interval between the rollingelements as short as possible, whereby the interval between the rollingelements has never been made large. However, in a case of a wheel for awheelchair, having a strength capable of supporting the weight of a userand the weight of the wheelchair itself (at least the chair unit and theinner ring) is merely required. Usually, strength for supporting aweight less than 100 kg is enough, so it is possible to reduce thenumber of rolling elements. Accordingly, by setting the length of thespacer appropriately as described above, it is possible to adapt thenumber of rolling elements to the weight of a user and the weight of thewheelchair. As a result, the number of the rolling elements can bereduced as much as possible, and resistance caused by rolling of therolling elements can be reduced, whereby it can preferably avoid wastingthe user's physical energy.

Each spacer is in a pipe-shape or in a rod-shape, for example. A hollowspacer is preferable, since the weight can be further reduced. Further,in order to prevent inhibition of rotation of the rolling elements bycontacting the spacer, it is preferable that at least the portions ofthe spacers in contact with the rolling elements be formed of a memberbe lubricated with respect to the rolling element. Alternatively, alubricant may be applied to a contacting face of the spacer so as toreduce the contact resistance with respect to the rolling element.

Further, it is preferable that a contact face of each spacer be formedcorresponding to the arcuate shape of the rolling face of the rollingelement. When the contact face is formed along the arcuate shape of therolling element in this way, rolling of the rolling element becomessmooth, and the state between the rolling elements and the spacersbecomes stable. Further, when the spacer is in a pipe shape and a sphere(ball) is used as the rolling element, the ball can be disposed so as tobe fit in an opening or “mouth” of the pipe-shaped spacer. Thereby, astate between the ball (rolling element) and the spacer becomes stableas described above, and each spacer can be manufactured by just cuttinga pipe-shaped member, which is easy.

Further, it is desirable for the shape of the spacer in a longitudinaldirection to be an arcuate shape adapting to the curvature of theannular space formed between the outer ring and inner ring. According tothis shape, the spacers can be disposed with little (or no) contact withthe outer ring and the inner ring, so there is little (or no) frictionalresistance between the spacer and the outer ring and the inner ring. Ifthe spacer is made of a flexible material, even though it is not formedby adapting to the curvature of the annular space accurately, or even itis a spacer of a linear shape, it can be disposed without any difficultyin a annular space by curving it. In this way, since a precise moldingis not required, it is possible to form spacers at low cost, which leadsto reduction in the manufacturing cost of wheels.

Further, if a lubricative material with respect to a rolling element,such as polyethylene terephthalate, polyacetal, or MC nylon, is used asa spacer, a rolling element rolls more smoothly, so the outer ringrotates more smoothly with respect to the inner ring.

As a type of rolling element, a roller or the like may be used insteadof a ball and as its material, any material having strength capable ofsupporting the weight of a user and the wheelchair itself, for example,metal or synthetic resin, may be used.

A wheelchair according to the present invention is characterized ofincluding the wheels for a wheelchair as described above. In particular,drive wheels of a wheelchair are large in size generally, so an effectof reducing weight or the like is significant. Therefore, it ispreferable to apply the wheels for a wheelchair described above to thisdrive wheel.

Further, a method of manufacturing a wheel for a wheelchair according tothe present invention is a method of manufacturing for a wheel for awheel chair including: an outer ring mounted on the inner periphery of atire; an inner ring which is concentric with the outer ring, positionedinside the outer ring, and connected to a wheelchair frame; a pluralityof rolling elements interposed between the outer ring and the innerring; and spacers provided between the rolling elements, respectively.The method comprises the steps of: determining the number of rollingelements adapting to a wheelchair user (hereinafter may be referred toas a number determining step); determining the length of the spacersaccording to the number of rolling elements determined and thecircumferential length of a circumferential space (annular space)defined between the outer ring and the inner ring (hereinafter may bereferred to as a length determining step); and disposing the rollingelements and the spacers between the outer ring and the inner ring(hereinafter may be referred to as an assembling step).

In this way, by changing the number of rolling elements and the lengthof spacers corresponding to the weight of a user or the like, it ispossible to reduce the weight of a wheel for a wheelchair by furtherreducing the number of the rolling elements, in a case of a light weightuser. On the other hand, it is possible to form a wheel having thenumber of rolling elements capable of keeping a sufficient strengthwhile reducing the weight, in a case of a heavy weight user.

Further, it is preferable to prepare a flexible long member beforehandas a spacer, which is cut corresponding to the length of the spacerdetermined by the length determining step so as to form the spacers(hereinafter, this step may be referred to as a spacer producing step).According to this, it is not necessary to prepare spacers of variouslengths, whereby the manufacturing cost can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view showing a wheelchair according to an embodiment 1of the present invention.

FIG. 2A is a partially broken side view showing a drive wheel of thewheelchair of the embodiment 1, and FIG. 2B is a sectional enlarged viewtaken along the line C-C shown in FIG. 2A.

FIG. 3 is a one-side sectional exploded perspective view of a drivewheel in the embodiment 1.

FIG. 4 is an enlarged perspective view showing a retainer in theembodiment 1.

FIG. 5 is a one-side sectional exploded perspective view showing aninner wheel and a mounting member for a frame in the embodiment 1.

FIG. 6A is a side view diagram, and FIG. 6B is a corresponding frontview diagram, showing a drive wheel (wheel for wheel chair) according toan embodiment 2 of the present invention.

FIG. 7A is a side view diagram illustrating a state of an existing drivewheel of a wheelchair (eg. wheelchair of the conventional example 1),and FIG. 7B is a side view diagram, showing a state in which theconventional wheel is replaced with a drive wheel of the presentembodiment 2.

FIG. 8 is a perspective view showing a wheelchair according to anembodiment 3 of the present invention.

FIG. 9 is a perspective view showing another example of a wheelchairaccording to the present invention.

FIG. 10 is a side view showing another example of a wheel for awheelchair according to the present invention.

FIG. 11 is a perspective view showing a conventional, self-travelingmanual wheelchair.

FIG. 12A is a side view diagram, and FIGS. 12B and 12C are correspondingperspective views, showing a wheelchair of the convention example 2.

FIG. 13A is a diagram showing an exemplary wheelchair of theconventional example 3, in which a partially broken perspective view ofa drive wheel thereof is shown, and FIG. 13B is a sectional view takenalong the line B-B shown in FIG. 13A.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1

FIG. 1 is a side view showing a wheelchair 10 according to an embodiment1 of the present invention. Hand rims 56 are omitted in Figure. Further,FIG. 2A is a partially broken side view showing a drive wheel 11 of thewheelchair 10, and FIG. 2B is a sectional enlarged view taken along theline C-C shown in FIG. 2A. FIG. 3 is a exploded perspective view of thedrive wheel 11. The same components as those in FIG. 11 and FIG. 12 aredenoted by the same reference numerals, and overlapping explanations areomitted.

The drive wheel 11 consists of a rubber tire 12, a metallic (e.g.,aluminum) outer ring 13 mounted on the inner periphery of the tire 12, ametallic (e.g., aluminum) inner ring 15 which is concentric with theouter wheel 13 and positioned inside the outer ring 13, twelve balls(rolling elements) 17 interposed between the outer ring 13 and the innerring 15, twelve retainers (spacers) 18 interposed between the balls 17,and a mounting member for a frame 14 mounted to the wheelchair frame 65.

The ball 17 is a sphere made of metal or hard synthetic resin such asphenol resin. On the other hand in which arcuate grooves 13 a and 15 aare formed in opposite faces of the outer ring 13 and the inner ring 15,respectively, so as to fit to the ball 17, as shown in FIG. 3. That is,the diameter of the ball 17 is the same as the spacers W.sub.1 betweengroove 13 a and groove 15 a of an annular space 16 formed by the groove13 a of the outer ring 13 and the inner wheel 15. The sizes of theplural balls 17 are the same.

FIG. 4 is an enlarged perspective view showing the retainer 18. Theretainer 18 is made of flexible synthetic resin such as polyethyleneterephthalate and the like, and is in a pipe shape. The longitudinaldirection thereof is curved arcuately so as to be almost along thecurvature in a peripheral direction of the annular space 16. The ball 17is fit in an opening 18 a at an end of the retainer 18. The widthW.sub.2 of the retainer 18 is smaller than the width W.sub.1 of theannular space 16, and the length L.sub.2 is a distance between the ball17 and the ball 17 (FIG. 2B, FIG. 4). All of the plural retainers 18have the same diameter W.sub.2 and the same length L.sub.2,respectively.

The outer ring 13 has a tire mounting members groove 13 b formed in theouter peripheral face thereof, and the tire 12 is mounted thereto, asdescribed above. Further, the outer ring 13 has a handle mountingmembers hole 13 c to which a handle rim 56 is mounted (FIG. 2B).

FIG. 5 is a exploded perspective view showing the inner ring 15 and themounting member 14 for a frame. The inner peripheral face of the innerring 15 has a mounting groove 15 b into which the mounting member for aframe 14 can be fitted and screwed. In FIG. 5, 15 c shows a screw holeformed in the inner ring, and 14 c is a screw hole for fixing the innerring, formed in the mounting member for a frame 14.

The mounting member for a frame 14 is further screwed to the frame 65with mounting screws 19. In FIG. 5, 14 a is a screw hole for fixing theframe, formed in the mounting member for a frame 14 (FIGS. 1, 5).

In this way, the inner ring 15 is connected with the wheelchair frame 65via the mounting member 14 for a frame. As shown in FIG. 1, in thepresent embodiment 1, the inner ring 15 is fixed at two points of anupper part and a lower part of the inner ring so a large space isprovided inside the drive wheel.

As shown in FIG. 2B, to bank parts 13 d and 15 d on the both lateralsides of the grooves 13 a and 10 a (see also FIG. 3) in the oppositefaces of the outer wheel 13 and the inner ring 15, seal 22 are mountedso as to prevent mud or the like from entering into the annular space16.

Next, a method of manufacturing the drive wheel 11 will be described.

The weight of a wheelchair 10 itself does not differ a lot from one toanother, but the load applied to the drive wheel 11 varies depending onthe weight of a user. Therefore, first, the number of balls 17 requiredfor supporting the load of a user and the wheelchair 10 itself isdetermined in consideration of the weight of the user (twelve balls inthe example shown) (number determining step). Next, the length L.sub.2of the retainer 18 is determined, based on the number of balls (lengthdetermining step). At this time, if the balls 17 are arranged evenly onthe circumference of the annular space 16, the lengths of respectiveretainers 18 are set to be the same. For example, if twelve balls 17having a diameter of 16 mm are used in a case where the diameter of theannular space 16 (which is a diameter of a circle pass through thecenter of the spacers W.sub.1, that is, a diameter of a circle definedby lines connecting the center of the balls 17 and the central axis ofthe retainers 18 arranged) is 512 mm, the length L.sub.2 of eachretainer 18 is 118 mm. Next, a long flexible pipe member, curved almostalong the curvature of the annular space 16 is prepared, and theflexible pipe member is cut to have the length L.sub.2 and is used asthe retainer 18 (spacers-member producing step). Then, inside theannular space 16, the number of balls 17 and the retainers 18,determined as described above, are arranged alternately (arranged suchthat a part of the ball 17 is fit in an opening 18 a of the retainer18), and the outer ring 13 and the inner ring 15 are assembled(assembling step), whereby the drive wheel 11 is completed.

When driving the wheelchair 10, the hand rims 56 are rowed so as torotate the tires 12 with the outer rings 13, whereby the wheelchair 10travels. At this time, the balls 17 roll inside the groove 13 a of theouter ring 13 and inside the groove 15 a of the inner ring 15, and theinner ring 15 is not rotated. Further, the balls 17 receive the load ofthe chair unit 60 applied to the inner ring 15, and the load is furtherreceived by the outer ring 13 and is supported on the ground by thetires 12.

The drive wheel 11 of the present embodiment 1 uses only twelve balls17, and the material itself of the retainer 18 is light, and further, itis hollow, so the drive wheel 11 is relatively light as a whole.Consequently, the weight of the wheelchair 10 as a whole is also light.Accordingly, the load placed on a user of the wheelchair when the userrows the wheelchair is reduced. Further, since the configuration of thedrive wheel 11 is relatively simple, the manufacturing cost is alsoreduced. Moreover, since the inner ring 15 does not rotate duringtraveling of the wheelchair 10, clothes are not rubbed and damaged evenif the clothes contact the inner ring 15. Further, since there is nospoke or the like inside the drive wheel 11 so a large space isprovided, and baggage can be put into or taken out against the baggagebasket 70 under the seat surface.

Further, the retainer 18 made of polyethylene terephthalate has thelubricity with respect to the ball 17, whereby rotation of the drivewheel 11 is performed smoothly.

Embodiment 2

FIG. 6A is a side view showing a drive wheel (wheel for a wheelchair) 21according to an embodiment 2 of the present invention, and FIG. 6B is afront view thereof.

The drive wheel 21 of the second embodiment 2 is one in which themounting member for a frame 14 in the drive wheel 11 of the embodiment 1is replaced with a mounting member for a hub 24, and the otherconfiguration is the same as that of the drive wheel 11 of theembodiment 1.

The mounting member for a hub 24 has leg parts 24 a, 24 b and 24 cextending in three directions from the rotational center (rotationalcenters of the inner wheel 15 and the outer ring 13) of the drive wheel21, and spaces 26 a, 26 b and 26 c are defined between the leg parts 24a, 24 b and 24 c, respectively. The top parts of the leg parts 24 a, 24b and 24 c are fixed by welding to the inner peripheral face of theinner ring 15. Further, to the rotational center of the drive wheel 21,a connecting member 25 extending toward the chair unit 60 side isprovided, which is attachable/detachable to the hub mounting memberspart 57 of a wheelchair having the hub 55 like the conventional example1.

FIG. 7 is a diagram illustrating a state where the drive wheel 51 of anexisting wheelchair (e.g., a wheelchair of the conventional example 1)is replaced with the drive wheel 21 of the present embodiment 2, FIG. 7Ais a side view showing the state of the existing wheelchair, and FIG. 7Bis a side view showing a state where the wheel is replaced with that ofthe present embodiment 2. The hand rim 56 is omitted in Figure.

In the existing wheelchair 50 having a hub, the drive wheel 51 isattachable/detachable in general (FIG. 7A), and this drive wheel 51 isdetached and the drive wheel 21 of the embodiment 2 is attached to thehub mounting members part 57 (FIG. 7B). By using the drive wheel 21 inthis way, the existing wheelchair 50 with a hub and spokes can bechanged to a wheelchair 20 without a hub and spokes.

In the wheelchair 20 with the drive wheel 21 of the embodiment 2, theinner ring 15 and the mounting member for a hub 24 do not rotate.Therefore, even when clothes or the like contact the inner ring 15 orthe mounting member for a hub 24, the clothes will never be rubbed anddamaged, as same as the case of the embodiment 1. Further, three largespaces 26 a, 26 b and 26 c are defined inside the drive wheel 21, sobaggage can be easily put into or taken out from the baggage basket 70under the seat surface 61.

Embodiment 3

FIG. 8 is a perspective view showing a wheelchair 30 according to anembodiment 3 of the present invention, which is a wheelchair for playingquad rugby.

A drive wheel of the wheelchair 30 of the embodiment 3 is the same asthe drive wheel 11 used in the embodiment 1, provided that the drivewheel 30 is mounted to the frame 65 via the mounting member 14 for aframe at five points in the present embodiment 3, although the drivewheel 11 is mounted to the frame 65 at two points in the embodiment 1.Further, protective boards 35 are disposed so as to surround the chairunit 60, the drive wheel 11 and casters (not shown) of the wheelchair.

Quad rugby is a strenuous sport in which wheelchairs crash into eachother. Therefore, since the chair unit 60 and the drive wheel 51 areconnected via the hub 55 like the conventional example 1, a shockapplied to the drive wheel 51 concentrates on the hub 55, whereby thewheel rotating axis of the hub 55 is deformed, as a result, defectivetraveling may be caused. In this aspect, in the present embodiment 3,the chair unit 60 and the drive wheel 11 are connected at five pointsvia the mounting member 14 for a frame, whereby a shock applied to thedrive wheel 11 is dispersed, so the drive wheel 11 is less likely to bedeformed and seldom causes defective traveling.

According to the wheelchair of the present invention as described above,by increasing the contacting points between the frame 65 and the drivewheel 11, the intensity is improved. Therefore, the wheelchair is usablefor a strenuous sport such as quad rugby. Further, the intensity canalso be improved not only by relatively increasing the connecting partsbetween the frame 65 and the drive wheel 11 but also by increasing thewidth of the connecting parts.

As described above, wheelchairs, wheels for wheelchairs, and a method ofmanufacturing wheels for wheelchairs according to the present inventionhave been explained specifically with reference to the drawings showingexamples. However, the present invention is not limited to the examplesshown, and may be carried out by applying appropriate modificationswithin the scope adaptable to the purport described above, all of whichare included in the technical scope of the present invention.

For example, although a pipe-shaped retainer is used as the retainers(spacers) 18 in the embodiments described above, it is not limited tothis shape and may be a rod shape for example, or may be a continuedshape by connecting adjacent retainers at a part. Further, in producingthe retainer 18 in the embodiments described above, a long materialwhich has been curved almost along the curvature of the annular space 16is used as the material. However, if the retainer is made of a flexiblematerial, it is not necessarily along the curvature of the annular space16, and may be in a linear shape. Since the retainer is made of aflexible material, it can be made to be along the curvature of theannular space 16 easily.

Further, although lengths of a plurality of retainers 18 are the same inthe embodiments described above, lengths of the respective retainers 18may be different. In such a case, the load can be supported more firmlyby arranging the retainers 18 and the balls 17 in the ring-ring space 16in such a manner that a larger number of balls 17 are positioned in thelower part of the wheel. However, if it is expected that the positionsof the retainers 18 and the balls 17 are shifted by driving thewheelchair, it is preferable for the balls 17 to be arranged evenly asthe embodiment 1. In a case of the lengths of the retainers 18 beingdifferent, the number of balls 17 positioned in the lower part may bereduced due to a shift. In such a case, the load of the weight or thelike of the user concentrates on the reduced number of balls 17, so aproblem may be caused in the aspect of intensity. However, in the caseof one in which balls 17 are arranged evenly, a constant intensity canbe kept with any shift.

Further, the connecting points of the inner ring 15 with respect to theframe 65 are two points in the embodiment 1, and are five points in theembodiment 3. However, the present invention is not limited to thesenumbers of the connecting points. For example, as shown in FIG. 9 [aperspective view showing another example of a wheelchair according tothe present invention], it may be fixed at four points with the fourmounting members 14 for a frame, or may be fixed at one point, threepoints or six points or more. Further, although the mounting member fora hub 24 which is divided in three extending ways is used in theembodiment 2, the present invention is not limited to the mountingmember for a hub 24 which is divided in three extending ways. Forexample, the mounting member for a hub 34 in which two legs 34 a and 34b are extending as shown in FIG. 10 [a side view showing another exampleof a wheel for a wheelchair according to the present invention], or amounting member for a hub having four or more legs may be used. However,if a mounting member for a hub has too many legs, the space inside thedrive wheel cannot be made large. Therefore, in view of this point, thelegs should not be too many.

Although it is needless to say that the drive wheel 11 described byusing FIG. 2 and the like is preferable as a wheelchair, it is alsoapplicable to other uses.

As described above, wheels for a wheelchair and wheelchairs according tothe present invention are light, so a load placed when carrying it by awheelchair user is reduced, and a burden placed when a carrier holds thewheelchair with the user for example, is also reduced. In addition,since the configuration is simple, the manufacturing cost is not high.Further, since the inside of a wheel does not rotate, there is noconcern about clothes being damaged by being rubbed. Moreover, since asufficiently large space can be provided inside the wheel baggage can beput in or taken from under the seat surface easily by using such aspace.

Further, according to the method of manufacturing a wheel for awheelchair of the present invention, it is possible to manufacture awheel for a wheelchair as described above appropriately.

1. A wheel for a wheelchair comprising: an outer ring mounted on aninner periphery of a tire; an inner ring which is positionedconcentrically inside the outer ring, and fitted on a wheelchair frame;a plurality of rolling elements interposed between the outer ring andthe inner ring, each rolling element being spaced at intervals in acircumferential direction; and a plurality of spacers for maintainingsaid intervals between the rolling elements, wherein each spacer is inan elongated shape along a circumferential direction of the outer ringand the inner ring, and each of the spacers and each of the rollingelements are alternatively provided along the circumferential direction.2. The wheel for the wheelchair as claimed in claim 1, wherein thespacer is made of a flexible material and is bent along thecircumferential direction.
 3. A wheel for a wheelchair comprising: anouter ring mounted on an inner periphery of a tire; an inner ring whichis positioned concentrically inside the outer ring, and fitted on awheelchair frame; a plurality of rolling elements interposed between theouter ring and the inner ring, each rolling element being spaced atintervals in a circumferential direction; and a plurality of spacers formaintaining said intervals between the rolling elements, wherein eachspacer is in an elongated shape along a circumferential direction of theouter ring and the inner ring, and each of the spacers and each of therolling elements are alternatively provided along the circumferentialdirection; and wherein each rolling element is spherically-shaped andeach spacer is pipe-shaped, and each rolling element is in contact withan opening mouth of a spacer.
 4. A wheelchair having a wheel accordingto claim
 1. 5. A wheelchair having a wheel according to claim
 2. 6. Awheelchair having a wheel according to claim
 3. 7. A method ofmanufacturing a wheel for a wheelchair having an outer ring mounted onan inner periphery of a tire, an inner ring which is positionedconcentrically inside the outer ring and defining an annular spacetherebetween, the inner ring being fitted on a wheelchair frame, aplurality of rolling elements interposed between the outer ring and theinner ring, and spacers provided between the rolling elements,respectively, the method comprising the steps of: determining a numberof the rolling elements adapted to suit a wheelchair user; determining alength of each spacer according to the number of rolling elementsdetermined and a circumferential length of the annular space definedbetween the outer ring and the inner ring; and disposing the rollingelements and the spacers between the outer ring and the inner ring in amanner that each of the spacers is arranged between adjacent rollingelements.
 8. The method of manufacturing the wheel for the wheelchair asclaimed in claim 7, further including the step of cutting a flexiblemember corresponding to the length of each spacer determined so as toform each spacer.
 9. The wheel for a wheelchair according to claim 1,wherein each spacer is made of lubricative material at least in an areain contact with the rolling element.
 10. The wheel for a wheelchairaccording to claim 9, wherein the spacers are made of polyethyleneterephthalate.
 11. The wheel for a wheelchair according to claim 1,wherein each spacer has a same length.
 12. The wheel for a wheelchairaccording to claim 1, wherein the wheel is used as a drive wheel for thewheelchair.